Thin layer accurate perforation device and method for highly-deviated extended reach well

Abstract

The invention relates to the field of oil-gas field development, and discloses a thin-layer precise perforation device and method for a highly-inclined and extended-reach well, a two-stage hydraulic compact type blowout prevention box is connected to an oil pipe, is special cable sealing equipment additionally arranged at a well mouth in the pumping process, and is used for ensuring that pumped liquid flows out only from an annular bypass and does not overflow from the well mouth; wellhead pressure cannot leak, and the logging instrument can be conveyed in place by controlling the pressure in the tubular column; a low-friction roller tool, a pitching unlocking pressure detonating device and a magnetism releasing combination instrument are arranged in an oil pipe, the position of a depth correction short section in the oil pipe can be effectively detected in the oil pipe through the low-friction roller tool and the magnetism releasing combination instrument driven by a cable, errors can be greatly reduced, it is ensured that a perforating gun is accurately aligned with a perforating layer, and the perforating efficiency is improved. And safe detonation of the perforator is ensured by unlocking the pressure detonation device through ball throwing, so that the error perforation risk in the instrument pumping process is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas field development, and in particular to a device and method for precise thin-layer perforation in high-angle and large-displacement wells. Background Art

[0002] Perforating is an important process in the oil and gas development process. To ensure that the perforator can accurately aim at the target layer, it is necessary to calibrate the depth of the perforator in the wellbore (hereinafter referred to as depth calibration). The depth of the perforator is calibrated to the depth of the logging results map, and the depth of the tubing is adjusted to make the perforator aim at the target layer for perforation.

[0003] At present, the depth calibration method used for tubing conveying perforation is to install a tubing short joint (or radioactive short joint) in the tubing string above the perforator as a depth calibration mark, and then lower an equal length of tubing according to the depth of the perforation target layer. However, due to the different depth starting points and conveying media, the engineering depth of the tubing is not equal to the depth of the logging interpretation curve, so it is necessary to calibrate the depth of the perforation string to the depth of the logging curve. Use the logging cable to carry the logging instrument into the tubing, and measure the natural gamma (GR) and tubing collar (CCL) curves at the same time. The depth of the measured GR and CCL curves is calibrated to the depth of the logging interpretation curve, and the depth of the calibration mark is read on the curve chart, and then the error between the tubing string and the target layer is determined, and the length of the tubing string is adjusted to accurately align the perforator with the target layer, and then the perforator is detonated to perforate. Cable logging relies on the deadweight of the instrument and the cable to be lowered into the well. In a well with a well inclination of less than 60°, it can be smoothly lowered to the target layer section, and the depth calibration is successful once. However, in highly deviated wells with inclination greater than 60° and in highly deviated and large displacement, cable logging cannot reach the target layer by its own gravity. It is necessary to run multiple depth calibration short sections in the well section with an inclination less than 60°. Through multiple depth calibrations, the length of the tubing entering the well is calibrated in sections, and the depth of the tubing is finally determined by the method of accumulating lengths. The multiple depth calibration method increases the perforation depth error, especially for some thin inter-oil layers. The large depth error directly leads to the failure to perforate the oil layer, and even worse, the water layer is perforated, which seriously affects the oil well production. At the same time, multiple depth calibrations extend the operation cycle and increase construction costs and risks. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a device and method for precise perforating of thin layers in highly inclined and large displacement wells, so as to solve the technical problem that the method of multiple depth calibrations for highly inclined well sections in the prior art increases the perforation depth error, prolongs the operation cycle, and increases the construction cost and risk.

[0005] The present invention is achieved through the following technical solutions:

[0006] A device for precise perforating of thin layers in high-angle and large-displacement wells, comprising a two-stage hydraulic compact blowout preventer box, a depth calibration short joint and a perforating gun string mounted on an oil pipe, as well as a low-friction roller tool, a ball-throwing unlocking pressure detonating device and a magnetic release combination instrument arranged in the oil pipe; the oil pipe extends into the wellhead and is sleeved in the casing in the wellhead; the two-stage hydraulic compact blowout preventer box is connected to one end of the oil pipe outside the wellhead, the depth calibration short joint is connected to the other end of the oil pipe in the wellhead, the perforating gun string is arranged on the depth calibration short joint, a cable runs through the two-stage hydraulic compact blowout preventer box, the cable extends into the oil pipe through the two-stage hydraulic compact blowout preventer box, the low-friction roller tool is arranged on the end of the cable extending into the oil pipe, and the magnetic release combination instrument is arranged on the low-friction roller tool for detecting the position of the depth calibration short joint in the casing.

[0007] Preferably, a wellhead tee is provided between the two-stage hydraulic compact blowout preventer box and the oil pipe, the vertical ends of the wellhead tee respectively connect the ports of the two-stage hydraulic compact blowout preventer box and the oil pipe, and the vertical port of the wellhead tee is connected to the liquid injection device.

[0008] Preferably, the inclination angle of the casing in the wellhead is greater than 60 degrees, and the oil pipes are coaxially distributed in the casing.

[0009] Preferably, the two-stage hydraulic compact blowout preventer box includes a union, a primary hydraulic control head and a secondary hydraulic control head, the secondary hydraulic control head is coaxially assembled with the primary hydraulic control head, and a grease injection bin is provided between the secondary hydraulic control head and the primary hydraulic control head, a grease injection nozzle is provided on the grease injection bin, one end of the union is assembled on the primary hydraulic control head, and the other end is connected to one end of the oil pipe outside the wellhead, and the cable extends into the oil pipe through the secondary hydraulic control head, the primary hydraulic control head and the union.

[0010] Furthermore, both the secondary hydraulic control head and the primary hydraulic control head are provided with a sealing rubber core, and the cable passes through the sealing rubber cores of the secondary hydraulic control head and the primary hydraulic control head in sequence, wherein the inner groove of the sealing rubber core and the contact surface of the cable are a conical structure, and the outer side of the sealing rubber core is sleeved on the spring rubber core, and the spring rubber core is axially contracted by the hydraulic action, squeezing the internal sealing rubber core and pressing the cable inside the sealing rubber core.

[0011] Preferably, the low-friction roller tool includes a rod-shaped tool body, an upper female connector, a lower male connector and a plurality of wheel pieces; a through-core conductor is arranged in the rod-shaped tool body, the upper female connector and the lower male connector are respectively arranged at the two ends of the rod-shaped tool body, the upper female connector is connected to the cable and the bridle, the lower male connector is connected to the magnetic release assembly instrument, the plurality of wheel pieces are rollingly connected in the rod-shaped tool body, and the plurality of wheel pieces are in rolling contact with the inside of the oil pipe.

[0012] Preferably, the ball-throwing unlocking pressure detonating device comprises an unlocking body and a steel ball; a shear ball seat is provided in the unlocking body, and a shear pin is provided between the shear ball seat and the inner wall of the unlocking body; a through hole is provided in the shear ball seat, and the aperture of the through hole corresponds to the ball diameter of the steel ball, and an impact sleeve is also provided in the unlocking body, and the impact sleeve is located at the outlet end of the through hole, and the steel ball hits the impact sleeve through the through hole, and a steel ball, a firing pin and a detonator are provided in the impact sleeve, and the steel ball is used to lock the firing pin, and one end of the firing pin is connected to the detonator; a plurality of sealing rings are provided between the impact sleeve and the inner wall of the unlocking body; the steel ball passes through the wellhead along the oil pipe to the unlocking body.

[0013] Furthermore, a plurality of circulation holes are provided on the unlocking body, and the circulation holes form oil and gas production channels on the unlocking body for circulating the oil and gas inside the unlocking body.

[0014] Preferably, a plurality of perforations are distributed in an annular pattern on the perforating gun string, and the perforation direction is perpendicular to the inner wall of the casing.

[0015] A method for precise perforating thin layers in highly deviated and extended-reach wells, based on the above-mentioned precise perforating device for precise perforating thin layers in highly deviated and extended-reach wells, comprises the following process:

[0016] In the high-angle and large-displacement TCP perforating construction, the perforating gun string, ball-dropping and unlocking pressure detonator, tubing, and depth-calibration short sub are sequentially lowered into the well according to the geological and engineering design;

[0017] Before depth calibration, the upper end of the tubing is connected to a two-stage hydraulic compact blowout preventer to effectively control the wellhead pressure during the depth calibration cable operation process; the cable carrying the magnetic release combination instrument and the low-friction roller tool is lowered into the tubing. When the depth calibration instrument encounters resistance, the pump truck is started to inject liquid into the tubing at a certain displacement. The instrument produces a piston effect in the tubing, and the thrust generated by the liquid flow pushes the instrument to continue moving downward until it reaches the depth calibration nipple. Special software is used to simulate the entire pumping process according to the wellbore trajectory and the structure of the instrument string entering the well, guiding the pumping displacement at different depths, so that the pumping instrument process is safe and controllable;

[0018] Lift the instrument from the wellhead, measure the GR and CCL curves, calibrate the measured GR curve to the depth of the logging interpretation curve, and then determine the actual depth of the depth calibration short sub. Adjust the perforating string according to the depth of the depth calibration short sub so that the perforator faces the target layer.

[0019] Install the Christmas tree, throw a steel ball into the tubing, start the pump truck to deliver the ball into position, and after the pressure display appears, continue to pressurize until the detonation pressure set by the ball-throwing unlocking pressure detonator is reached, detonate the perforating gun to perforate, and after perforating is completed, proceed to the next step.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] The present invention provides a thin-layer precision perforating device for high-angle and large-displacement wells. The device is a special cable sealing device installed at the wellhead during the pumping process by connecting a double-stage hydraulic compact blowout prevention box to the oil pipe. The device is used to ensure that the pumped liquid only flows out from the annulus bypass and does not overflow from the wellhead, and the wellhead pressure does not leak. The pressure in the pipe string is controlled to ensure that the logging instrument is delivered to the right place. A low-friction roller tool, a ball-throwing unlocking pressure detonating device and a magnetic release combination instrument are installed in the oil pipe. The low-friction roller tool and the magnetic release combination instrument are driven by cables in the oil pipe to effectively detect the position of the depth calibration short section in the oil pipe, which can greatly reduce the above-mentioned error, ensure that the perforating gun is accurately aligned with the perforating layer, and ensure the safe detonation of the perforator by the ball-throwing unlocking pressure detonating device. Before the ball-throwing operation detonating device is actuated, the perforator will not be accidentally detonated by the high pressure generated by the bottom hole pressure fluctuation. The device is a safe pressure detonating device, which greatly reduces the risk of mis-perforating during the pumping of the instrument.

[0022] Furthermore, the double-stage hydraulic compact blowout preventer adopts a double blowout preventer design and a hydraulically controlled sealing mechanism. Two hydraulic control heads are used to seal the cable. A grease injection and spray release interface is left between the two control heads. When used as a cable scraper, the overflow liquid can be sprayed from the grease injection chamber in the middle of the double control heads through the overflow pipeline to reduce the pollution of the well fluid brought out by the cable to the environment. The sealing pressure for the commonly used 8mm logging cable is >20MPa. The structure is compact and easy to disassemble and assemble. There is no need to remake the bridle for on-site operations. It can be quickly assembled and connected to the well, greatly improving construction efficiency. The internal parts of the double-stage hydraulic compact blowout preventer adopt a split structure. The parts inside the blowout preventer that contact the cable adopt a split structure. This structure allows the cable head to pass through the blowout preventer shell first, and then assemble the internal parts. It is easy to operate, saves the work of making the cable head on site, and improves the operation timeliness.

[0023] Furthermore, a low-friction roller tool refers to a special hydraulic conveying instrument. In the process of hydraulic conveying of logging instruments, reducing the sliding friction of the logging instruments is an important measure. The low-friction roller conveying tool is used to reduce the sliding friction of the logging instruments, convert the sliding friction into point contact rolling friction, reduce frictional resistance, and enhance the effect of gravity drive.

[0024] Furthermore, the ball-throwing unlocking pressure detonator refers to a pressure detonator that requires a ball. When the well inclination is greater than 60° and the well has a large inclination and large displacement, the pressure ignition detonator needs to be used. If the positioning instrument is pumped into place by hydraulic pushing, there will be a certain pump pressure in the tubing. At the same time, due to factors such as the diameter of the liquid circulation channel, liquid friction, and channel blockage, pressure fluctuations will occur at the bottom of the well. When the fluctuating pressure reaches the design pressure of the detonator, the detonator will be activated to detonate the perforator, causing misperforation, resulting in huge losses and well control risks. The ball-throwing pressure detonator is designed with a circulation channel to realize pumping circulation. When detonation is required, a steel ball is first dropped into the tubing column, and the steel ball is pumped to the ball seat of the detonator. The pin is sheared by pressurizing the tubing, so that the detonator is activated to detonate the perforator, and a circulation channel is formed again, which can be circulated to kill the well or put into production. The detonator is a pressure differential type, and it is in a pressure balance state before the steel ball is dropped, which has high safety.

[0025] The present invention provides a method for precise thin-layer perforation in highly inclined and extended-displacement wells. The above-mentioned error can be greatly reduced by means of a precise thin-layer perforation device for highly inclined and extended-displacement wells, ensuring that the perforating gun is accurately aligned with the perforating layer. The present invention only requires one depth calibration, thus saving working hours, reducing the connection of working procedures, and ensuring the continuity of the lower perforating string. By shortening the operation cycle, the oil well can be put into production ahead of schedule, with significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the thin layer precision perforating device used for high-angle and large-displacement wells in the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the double-stage hydraulic compact blowout prevention box in the present invention;

[0028] Figure 3 is a schematic diagram of a low-friction roller tool in the present invention;

[0029] Figure 4 This is a schematic diagram of the ball-throwing unlocking pressure detonation device of the present invention;

[0030] In the figure: 1 is a two-stage hydraulic compact blowout preventer box; 2 is a low-friction roller tool; 3 is a ball-throwing unlocking pressure detonator; 4 is a wellhead tee; 5 is a casing; 6 is a cable; 7 is a tubing; 8 is a magnetic release combination instrument; 9 is a depth calibration short joint; 10 is a perforating gun string; 1-1 is a union joint; 1-2 is a first-level hydraulic control head; 1-3 is a grease injection chamber; 1-4 is a grease injection and discharge nozzle; 1-5 is a second-level hydraulic control head; 1-6 is a spring rubber core; 1-7 is a sealing rubber core; 2-1 is a rod-shaped tool body;. 2-2 is the upper female joint; 2-3 is the lower male joint; 2-4 is the wheel; 3-1 is the unlocking body; 3-2 is the steel ball; 3-3 is the shear ball seat; 3-4 is the shear pin; 3-5 is the impact sleeve; 3-6 is the steel ball; 3-7 is the firing pin; 3-8 is the sealing ring; 3-9 is the detonator; 3-1-1 is the oil and gas production channel; 3-1-2 is the circulation hole. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0033] The purpose of the present invention is to provide a device and method for accurate perforation of thin layers in high-inclination and large-displacement wells, which can determine the depth of the deep mark by measuring the natural gamma (GR) and the tubing coupling (CCL) curves at one time, and then adjust the length of the pipe string to accurately align the perforator with the target layer, thereby avoiding the problem of increased perforation depth error caused by multiple depth calibrations and segmented cumulative length. This technology realizes a method for accurate one-time depth calibration perforation of thin layers by effectively using key technologies such as wellhead pressure control, efficient pumping, safe detonation, and abnormal construction situation handling.

[0034] See also Figure 1In one embodiment of the present invention, a thin-layer precision perforating device for high-angle and large-displacement wells is provided, comprising a two-stage hydraulic compact blowout prevention box 1, a depth calibration short sub 9 and a perforating gun string 10 mounted on a tubing 7, and a low-friction roller tool 2, a ball-throwing unlocking pressure detonating device 3 and a magnetic release combination instrument 8 arranged in the tubing 7; the tubing 7 extends in the wellhead and is sleeved in the casing 5 in the wellhead; the two-stage hydraulic compact blowout prevention box 1 is connected to one end of the tubing 7 outside the wellhead, the depth calibration short sub 9 is connected to the other end of the tubing 7 in the wellhead, the perforating gun string 10 is arranged on the depth calibration short sub 9, the two-stage hydraulic compact blowout prevention box 1 passes through a cable 6, and the cable 6 extends into the tubing 7 through the two-stage hydraulic compact blowout prevention box 1, the low-friction roller tool 2 is arranged on the end of the cable 6 extending into the tubing 7, and the magnetic release combination instrument 8 is arranged on the low-friction roller tool 2 for detecting the position of the depth calibration short sub 9 in the casing 5.

[0035] Specifically, a wellhead tee 4 is provided between the two-stage hydraulic compact blowout preventer box 1 and the oil pipe 7, the vertical ends of the wellhead tee 4 are respectively connected to the ports of the two-stage hydraulic compact blowout preventer box 1 and the oil pipe 7, and the vertical port of the wellhead tee 4 is connected to the liquid injection device.

[0036] Specifically, the inclination angle of the casing 5 in the wellhead is greater than 60 degrees, and the oil pipes 7 are coaxially distributed in the casing 5 .

[0037] Specifically, according to Figure 2 As shown, the two-stage hydraulic compact blowout preventer box 1 includes a union 1-1, a primary hydraulic control head 1-2 and a secondary hydraulic control head 1-5, the secondary hydraulic control head 1-5 is coaxially assembled with the primary hydraulic control head 1-2, and a grease injection bin 1-3 is provided between the secondary hydraulic control head 1-5 and the primary hydraulic control head 1-2, a grease injection outlet 1-4 is provided on the grease injection bin 1-3, one end of the union 1-1 is assembled on the primary hydraulic control head 1-2, and the other end is connected to one end of the oil pipe 7 outside the wellhead, and the cable 6 extends into the oil pipe 7 through the secondary hydraulic control head 1-5, the primary hydraulic control head 1-2 and the union 1-1.

[0038] Among them, both the secondary hydraulic control head 1-5 and the primary hydraulic control head 1-2 are provided with a sealing rubber core 1-7, and the cable 6 passes through the sealing rubber core 1-7 of the secondary hydraulic control head 1-5 and the primary hydraulic control head 1-2 in turn, wherein the inner groove of the sealing rubber core 1-7 and the contact surface of the cable 1-8 are conical structures, and the outer side of the sealing rubber core 1-7 is sleeved on the spring rubber core 1-6, and the spring rubber core 1-6 is axially contracted by the hydraulic action, squeezing the internal sealing rubber core 1-7, and pressing the cable 6 inside the sealing rubber core 1-7.

[0039] Among them, the outer layer of the sealing rubber core 1-7 is covered with a spring rubber core 1-6, and the spring rubber core 1-6 is axially contracted by the hydraulic pressure, squeezing the internal sealing rubber core 1-7, hugging the internal cable 1-8, and achieving a sealing effect. The inner groove of the internal sealing rubber core 1-7 of the double hydraulic control head and the contact surface of the cable 1-8 are conical structures. The hand pump pressure is adjusted according to the well pressure to increase the contact area between the rubber core and the cable, so as to achieve the effect of adjusting the sealing pressure. The bottom of the two-stage hydraulic compact blowout preventer is connected to the wellhead tee through the union 1-1.

[0040] Specifically, according to Figure 3 As shown, the low-friction roller tool 2 includes a rod-shaped tool body 2-1, an upper female connector 2-2, a lower male connector 2-3 and a plurality of wheel pieces 2-4; a through-core conductor is arranged inside the rod-shaped tool body 2-1, the upper female connector 2-2 and the lower male connector 2-3 are respectively arranged at the two ends of the rod-shaped tool body 2-1, the upper female connector 2-2 is connected to the cable 6 and the bridle, the lower male connector 2-3 is connected to the magnetic release assembly instrument 8, and the plurality of wheel pieces 2-4 are rollingly connected inside the rod-shaped tool body 2-1, and the plurality of wheel pieces 2-4 are rollingly contacted with the inside of the oil pipe 7.

[0041] Among them, during the hydraulic conveying of logging instruments, the wheel pieces 2-4 roll along the inner wall of the oil pipe under the thrust of the water flow, converting the sliding friction into point contact rolling friction. When pumping to calibrate the depth in a highly inclined well, the pumping pressure can be effectively reduced, and the magnetic combination instrument can be lowered into the depth calibration short section position to complete the depth calibration logging operation.

[0042] Specifically, according to Figure 4 As shown, the ball-throwing unlocking pressure detonating device 3 includes an unlocking body 3-1 and a steel ball 3-2; a shear ball seat 3-3 is provided in the unlocking body 3-1, and a shear pin 3-4 is provided between the shear ball seat 3-3 and the inner wall of the unlocking body 3-1; a through hole is provided in the shear ball seat 3-3, and the aperture of the through hole corresponds to the ball diameter of the steel ball 3-2, and an impact sleeve 3-5 is also provided in the unlocking body 3-1, and the impact sleeve 3-5 is located at the outlet end of the through hole, and the steel ball 3-2 hits the impact sleeve 3-5 through the through hole, and a steel ball 3-6, a firing pin 3-7 and a detonator 3-9 are provided in the impact sleeve 3-5, and the steel ball 6 is used to lock the firing pin 3-7, and one end of the firing pin 3-7 is connected to the detonator 3-9; a plurality of sealing rings 3-8 are provided between the impact sleeve 3-5 and the inner wall of the unlocking body 3-1; the steel ball 3-2 passes through the wellhead along the oil pipe to the unlocking body 3-1.

[0043] Among them, the internal striker 3-7 of the ball-throwing pressure detonator is locked by the φ8 steel ball 3-6, and the shear ball seat 3-3 is balanced in pressure on the upper and lower end surfaces in the oil pipe. After the perforating construction pipe string is lowered to the target layer, the φ38 steel ball 3-2 is dropped from the wellhead, and the φ38 steel ball 3-2 falls into the shear ball seat 3-3 in the unlocking body 3-1 to form a seal. When the wellhead is pressurized and the pressure reaches the shear value (15MPa) of the shear pin, the pin is sheared, and the shear ball seat 3-3 moves down under the pressure and hits the impact sleeve 3-5. At this time, the shear pin 3-4 is sheared, the impact sleeve 3-5 moves down, the φ8 steel ball 3-6 is unlocked, and the striker 3-7 releases the firing workpiece detonator 3-9 under the action of the well fluid pressure, thereby detonating the perforating gun.

[0044] Among them, a plurality of circulation holes 3-1-2 are provided on the unlocking body 3-1, and the circulation holes 3-1-2 form an oil and gas production channel 3-3-1 on the unlocking body 3-1 for circulating the oil and gas inside the unlocking body 3-1.

[0045] Among them, a number of circulation holes 3-1-2 are arranged on the unlocking body 3-1, which can be used as circulation channels for pumping instruments before pitching. After the striker 3-7 is released, the circulation holes 3-1-2 can be used as oil and gas production channels 3-3-1.

[0046] Specifically, a plurality of perforations are distributed in an annular pattern on the perforating gun string 10 , and the perforation direction is perpendicular to the inner wall of the casing 5 .

[0047] The present invention utilizes hydraulic pushing technology to deliver the logging depth calibration instrument to the perforating target layer, realizes effective control of the wellhead pressure by effectively using a two-stage hydraulic compact blowout preventer, efficiently pumps the tool through a low-friction roller tool, designs a ball-throwing unlocking pressure detonating device to ensure the safe detonation of the perforator, and is equipped with a steel ball salvage tool to handle abnormal construction situations.

[0048] The hydraulic pushing technology refers to the process of lifting and lowering the oil pipe to transport the perforating string. A bypass hole is designed in the string above the perforator, and a three-way short joint is installed on the wellhead string. Liquid is pumped into the tee and circulated in the bypass hole to the space between the wellbore and the string. This reciprocating process pushes the logging instrument forward to form a continuous pumping thrust. At the same time, the pumping program design is optimized for different well conditions and instrument string structures, and the maximum pressure of the wellbore is controlled. Under the premise of ensuring good dynamic sealing of the cable, the logging instrument can be safely transported to the place.

[0049] The present invention also provides a method for precise perforating thin layers in highly deviated and extended-reach wells, based on the above-mentioned precise perforating device for thin layers in highly deviated and extended-reach wells, comprising the following process:

[0050] In the high-angle and large-displacement TCP perforating construction, the perforating gun string 10, the ball-dropping and unlocking pressure detonator 3, the oil pipe 7, and the depth-calibration short sub 9 are sequentially lowered into the well according to the geological and engineering design;

[0051] Before depth calibration, connect the upper end of the tubing 7 to the two-stage hydraulic compact blowout preventer box 1 to effectively control the wellhead pressure during the depth calibration cable operation process; lower the cable 6 carrying the magnetic release combination instrument 8 and the low-friction roller tool 2 into the tubing 7. When the depth calibration instrument encounters resistance, start the pump truck to inject liquid into the tubing at a certain displacement. The instrument produces a piston effect in the tubing, and the thrust generated by the liquid flow pushes the instrument to continue moving downward until it reaches the depth calibration short section 9. Use special software to simulate the entire pumping process according to the wellbore trajectory and the structure of the instrument string entering the well, guide the pumping displacement at different depths, and make the pumping instrument process safe and controllable.

[0052] The instrument is lifted up from the wellhead, and the GR and CCL curves are measured by logging. The measured GR curve is corrected to the depth of the logging interpretation curve, and then the actual depth of the depth calibration short sub is determined. The perforating string is adjusted according to the depth of the depth calibration short sub 9, so that the perforator is facing the target layer;

[0053] Install the Christmas tree, throw the steel ball 3-2 into the oil pipe, start the pump truck to send the ball into place, and after the pressure display appears, continue to pressurize to the detonation pressure set by the ball-throwing unlocking pressure detonator 3, detonate the perforating gun to perforate, and after completing the perforation, go to the next step.

[0054] The present invention aims to solve the problem that multiple depth calibration is required for perforating with large inclination and large displacement of tubing with well inclination greater than 60°, especially for some large displacement wells and horizontal wells, which require more than three depth calibrations. Compared with the traditional multiple depth calibrations, the present invention greatly improves the perforation accuracy. According to the perforation technical specifications, the error of the depth calibration of tubing perforation should not be greater than 0.2m. If the depth is calibrated multiple times, the errors of multiple mappings will accumulate, resulting in a large error in the final depth; multiple depth calibrations determine the depth by accumulating the length of the tubing string, and cannot eliminate the errors caused by the wellbore trajectory and the stretching and friction of the tubing string. The more depth calibrations, the greater the error. The present invention adopts a one-time depth calibration method, which can greatly reduce the above errors and ensure that the perforating gun is accurately aligned with the perforating layer. The present invention adopts a new type of ball-throwing pressure detonator. Before the ball-throwing operation detonator is actuated, the perforator will not be accidentally detonated due to the high pressure generated by the bottom hole pressure fluctuation. It is a safe pressure detonator, which greatly reduces the risk of mis-perforation during the pumping instrument process. Traditionally, a single depth calibration operation requires 5-6 hours, and multiple depth calibrations will double the working hours. The present invention only requires one depth calibration, which saves working hours, reduces the connection of working procedures, ensures the continuity of the perforating string, and shortens the operation cycle, so that the oil well can be put into production ahead of schedule, with significant economic benefits. The present invention has been successfully applied to more than 30 wells in Dagang Oilfield, Jidong Oilfield, CNOOC, and CNOOC (Zhanjiang), greatly improving the depth calibration accuracy of perforating wells with high deviations, and increasing the average operation time by 48.5%, showing broad application prospects. The maximum well inclination of the instrument string is 87°, the maximum horizontal displacement is 3050 meters, and the maximum wellhead control pressure is 8MPa. The time efficiency is improved from a maximum of five depth calibrations to one depth calibration. Specific examples are shown in Table 1;

[0055] Table 1. Case study of depth calibration construction in highly inclined wells.

[0056]

[0057]

[0058] Application Case 1: Zhuanghai XX Well, the depth calibration of the perforating string in three sections and four times was compared with the depth calibration of the pumping instrument once. By comparing the multiple depth calibration technology, this technology greatly improves the perforation accuracy. From Table 2, it can be seen that the difference in the adjustment amount of the string between the four-section depth calibration and the one-time pumping depth calibration is 1.42m. From a technical perspective, the one-time pumping depth calibration is more accurate.

[0059] Table 2 Comparison of 4-stage depth calibration and 1-time pumping depth calibration data

[0060]

[0061] Application Case 2: In the WZ-XX well, the three-time perforation string depth calibration and the one-time depth calibration of the pumping instrument were compared. According to the data comparison in Table 3, the time efficiency of the one-time depth calibration operation was reduced from 48 hours to 16 hours, and the time efficiency of the one-time depth calibration operation was significantly higher than that of multiple depth calibrations.

[0062] Table 3 Comparison of the effectiveness of three depth calibrations and one pumping depth calibration in a highly deviated well

[0063]

[0064] In summary, the present invention provides a device and method for precise perforating of thin layers in high-angle and large-displacement wells. A two-stage hydraulic compact blowout preventer is connected to the oil pipe, which is a special cable sealing device installed at the wellhead during the pumping process, and is used to ensure that the pumped liquid only flows out from the annulus bypass and does not overflow from the wellhead, and the wellhead pressure does not leak. By controlling the pressure in the tubing string, it is ensured that the logging instrument is delivered to the right place; and a low-friction roller tool, a ball-throwing unlocking pressure detonating device and a magnetic release combination instrument are installed in the oil pipe. The low-friction roller tool and the magnetic release combination instrument are driven by the cable in the oil pipe to effectively detect the position of the depth calibration short section in the oil pipe, which can greatly reduce the above-mentioned error, ensure that the perforating gun is accurately aligned with the perforating layer, and ensure the safe detonation of the perforator by the ball-throwing unlocking pressure detonating device. Before the ball-throwing operation detonating device is actuated, the perforator will not be accidentally detonated due to the high pressure generated by the bottom hole pressure fluctuation. It is a safe pressure detonating device, which greatly reduces the risk of mis-perforating during the pumping of the instrument.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A thin layer precision perforating device for high-angle and large-displacement wells. It is characterized in that The invention comprises a two-stage hydraulic compact blowout prevention box (1), a depth calibration short section (9) and a perforating gun string (10) mounted on an oil pipe (7), and a low-friction roller tool (2), a ball-throwing unlocking pressure detonation device (3) and a magnetic release combination instrument (8) arranged in the oil pipe (7); the oil pipe (7) extends into a wellhead and is sleeved in a casing (5) in the wellhead; the two-stage hydraulic compact blowout prevention box (1) is connected to one end of the oil pipe (7) outside the wellhead, and the depth calibration short section (9) is connected to the wellhead. At the other end of the inner oil pipe (7), the perforating gun string (10) is arranged on the depth calibration short section (9), the cable (6) runs through the double-stage hydraulic compact blowout prevention box (1), the cable (6) extends into the oil pipe (7) through the double-stage hydraulic compact blowout prevention box (1), the low-friction roller tool (2) is arranged on the end of the cable (6) extending into the oil pipe (7), and the magnetic release combination instrument (8) is arranged on the low-friction roller tool (2) for detecting the position of the depth calibration short section (9) in the casing (5).

2. A thin layer precision perforating device for high-angle and large-displacement wells according to claim 1, It is characterized in that A wellhead tee (4) is provided between the two-stage hydraulic compact blowout prevention box (1) and the oil pipe (7), the vertical ends of the wellhead tee (4) respectively communicate with the ports of the two-stage hydraulic compact blowout prevention box (1) and the oil pipe (7), and the vertical port of the wellhead tee (4) is connected to a liquid injection device.

3. The device for precise thin-layer perforation in high-angle and large-displacement wells according to claim 1, It is characterized in that The inclination angle of the casing (5) in the wellhead is greater than 60 degrees, and the oil pipes (7) are coaxially distributed in the casing (5).

4. A thin layer precision perforating device for high-angle and large-displacement wells according to claim 1, It is characterized in that The double-stage hydraulic compact blowout prevention box (1) comprises a union (1-1), a primary hydraulic control head (1-2) and a secondary hydraulic control head (1-5); the secondary hydraulic control head (1-5) is coaxially assembled with the primary hydraulic control head (1-2); a grease injection bin (1-3) is provided between the secondary hydraulic control head (1-5) and the primary hydraulic control head (1-2); a grease injection outlet (1-4) is provided on the grease injection bin (1-3); one end of the union (1-1) is assembled on the primary hydraulic control head (1-2), and the other end is connected to one end of an oil pipe (7) outside a wellhead; the cable (6) extends into the oil pipe (7) through the secondary hydraulic control head (1-5), the primary hydraulic control head (1-2) and the union (1-1).

5. A thin layer precision perforating device for high-angle and large-displacement wells according to claim 4, It is characterized in that The secondary hydraulic control head (1-5) and the primary hydraulic control head (1-2) are both provided with a sealing rubber core (1-7), and the cable (6) passes through the sealing rubber cores (1-7) of the secondary hydraulic control head (1-5) and the primary hydraulic control head (1-2) in sequence, wherein the inner groove of the sealing rubber core (1-7) and the contact surface of the cable (1-8) are of a conical structure, and the outer side of the sealing rubber core (1-7) is sleeved on the spring rubber core (1-6), and the spring rubber core (1-6) is axially contracted under the action of hydraulic pressure, squeezing the internal sealing rubber core (1-7) and pressing the cable (6) inside the sealing rubber core (1-7).

6. The device for precise thin-layer perforation in high-angle and large-displacement wells according to claim 1, It is characterized in that The low-friction roller tool (2) comprises a rod-shaped tool body (2-1), an upper female connector (2-2), a lower male connector (2-3) and a plurality of wheel pieces (2-4); a through-core conductor is arranged inside the rod-shaped tool body (2-1); the upper female connector (2-2) and the lower male connector (2-3) are respectively arranged at two ends of the rod-shaped tool body (2-1); the upper female connector (2-2) is connected to a cable (6) and a bridle; the lower male connector (2-3) is connected to a magnetic release assembly instrument (8); the plurality of wheel pieces (2-4) are rollingly connected inside the rod-shaped tool body (2-1), and the plurality of wheel pieces (2-4) are rollingly contacted with the inside of an oil pipe (7).

7. The device for precise thin-layer perforation in high-angle and large-displacement wells according to claim 1, It is characterized in that The ball-throwing unlocking pressure detonating device (3) comprises an unlocking body (3-1) and a steel ball (3-2); a shearing ball seat (3-3) is provided inside the unlocking body (3-1), and a shearing pin (3-4) is provided between the shearing ball seat (3-3) and the inner wall of the unlocking body (3-1); a through hole is provided inside the shearing ball seat (3-3), and the diameter of the through hole corresponds to the ball diameter of the steel ball (3-2); an impact sleeve (3-5) is also provided inside the unlocking body (3-1), and the impact sleeve (3-5) is located at the outlet end of the through hole. The steel ball (3-2) strikes the striking sleeve (3-5) through the through hole; a steel ball (3-6), a striker (3-7) and a detonator (3-9) are arranged inside the striking sleeve (3-5); the steel ball (6) is used to lock the striker (3-7); one end of the striker (3-7) is connected to the detonator (3-9); a plurality of sealing rings (3-8) are arranged between the striking sleeve (3-5) and the inner wall of the unlocking body (3-1); the steel ball (3-2) passes through the wellhead and along the oil pipe to the unlocking body (3-1).

8. A thin layer precision perforating device for high-angle and large-displacement wells according to claim 7, It is characterized in that The unlocking body (3-1) is provided with a plurality of circulation holes (3-1-2), and the circulation holes (3-1-2) form an oil and gas production channel (3-3-1) on the unlocking body (3-1) for circulating the oil and gas inside the unlocking body (3-1).

9. The device for precise thin-layer perforation in high-angle and large-displacement wells according to claim 1, It is characterized in that A plurality of perforations are distributed in an annular pattern on the perforating gun string (10), and the perforation direction is perpendicular to the inner wall of the casing (5).

10. A method for precise perforating thin layers in highly deviated and extended-reach wells, based on a device for precise perforating thin layers in highly deviated and extended-reach wells as claimed in any one of claims 1 to 9, It is characterized in that The process includes the following: In the high-angle and large-displacement TCP perforating construction, according to the geological and engineering design, the perforating gun string (10), the ball-dropping and unlocking pressure detonating device (3), the oil pipe (7), and the depth calibration short joint (9) are sequentially lowered into the well; Before the depth calibration, the upper end of the oil pipe (7) is connected to a two-stage hydraulic compact blowout prevention box (1) to effectively control the wellhead pressure during the depth calibration cable operation process; the cable (6) carrying the magnetic release combination instrument (8) and the low-friction roller tool (2) is lowered into the oil pipe (7); when the depth calibration instrument encounters resistance, the pump truck is started to inject liquid into the oil pipe at a certain displacement, and the instrument produces a piston effect in the oil pipe. The thrust generated by the liquid flow pushes the instrument to continue moving downward until it reaches the depth calibration short section (9). The entire pumping process is simulated using special software according to the wellbore trajectory and the structure of the instrument string entering the well, and the pumping displacement at different depths is guided, so that the pumping instrument process is safe and controllable; The instrument is lifted up from the wellhead, and the GR and CCL curves are measured by logging. The measured GR curve is corrected to the depth of the logging interpretation curve, and then the actual depth of the depth calibration short sub is determined. The perforating string is adjusted according to the depth of the depth calibration short sub (9) so that the perforator is facing the target layer; Install the Christmas tree, throw a steel ball (3-2) into the oil pipe, start the pump truck to send the ball into position, and after the pressure display appears, continue to pressurize to the detonation pressure set by the ball-throwing unlocking pressure detonator (3), detonate the perforating gun to perforate, and after perforating is completed, proceed to the next step.

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